Preparation of thermosetting binders from phenol derivatives of waste sulphite liquor



States PREPARATION OF THERMQSETTING BDJDERS FROM PHENOL DERIVATIVES {9F WASTE SULPHITE LIQUOR No Drawing. Application N ovemher 2, 1953,

7 Serial No. 339,864

Claims. (Cl. 260-175) This invention relates to a method for the preparation of a thermosetting binder from phenol derivatives of waste sulphite liquor and areactive aldehyde, in particular a binder which is suitable for the consolidation of finely divided wood waste, e. g., sawdust and shavings, into useful products such as wallboards, plywood corestock, etc. Present methods for the consolidation of such Wood wastes involve the use of expensive synthetic resin adhesives of the phenolformaldehyde, urea-formaladehyde or melamine formaladehyde type. The cost of these resin adhesives represents a large portion of the cost of the finished product. By our process a waste product, lignin, which has been rendered water soluble by the sulphite cooking process, is modified by chemical treatment to permit its use. as a binder in place of the synthetic resin adhesives at a considerable cost advantage. v

In the co-pending application of Harry Borden Marshall and Mary Krizsan, Serial No. 299,278, filed July 16, 1952, now Patent 2,772,140, a process was disclosed for the condensation of phenols with decationized waste sulphite liquor.

The process is briefly as follows: waste sulphite liquor is passed through a cation exchange column to remove calcium or any other cations present, the decationized liquor heated with a phenol, and the excess phenol removed.

We have now discovered that these phenol derivatives of waste sulphite liquor will react in aqueous solution with a reactive aldehyde such as formaldehyde or furfural to yield water-soluble condensation products with thermosetting properties, i. e., on further heating or drying they are converted to insoluble resins. condensation products of phenol derivatives of waste,'sulphite liquor with an aldehyde may be applied to shavings or other wood wastes, and then, by the further application of heat and pressure, converted to an insoluble resinous binding material.

While phenol derivatives of waste sulphite liquors prepared according to the process of the co-pending applica- Thus the water-solublev aren't tion of Harry Borden Marshall and Mary Krizsan, Serial No. 299,278, filed July 16, 1952, now Patent 2,772,140, are suitable for use in the present process to produce a thermosetting binder, it is to be understood that this invention is not to be limited to the treatment of only those phenol derivatives of waste sulphite liquors described and claimed in the said co-pending application. The process which forms the subject matter of this invention may be efiected using any phenol derivative of Waste sulphite liquor, however produced. it is, therefore, to be understood that where here and elsewhere in our specification and claims we use thewords phenol derivative of waste sulphite liquor, this phrase is to be construed as including all such phenol derivatives whether produced according to the teaching of the said co-pending application of Harry Borden Marshall and Mary Krizsan, or otherwise.

A process has been described (German Patent 593,505, issued on February .27, 1934) in which waste sulphite liquor, a phenol and an aldehyde are heated together in Harry Borden Marshall and Mary Krizsan Serial No. 299,278, now Patent 2,772,140, before any aldehyde is added. This ensures the presence of suflicient phenolic groups in the lignin so that on subsequent reaction with an aldehyde, a water-soluble thermosetting compound is formed which on further heating becomes insoluble in water.

We have found that the characteristics of binders prepared by the method of our invention depend on a numer of factors, (a) the type and amount of phenol used for condensation with the waste sulphite liquor, (b) the type and amount of aldehyde used for condensation with the phenol derivative of Waste sulphite liquor, (c) the degree of pre-curing of the phenol-waste sulphite liquoraldehyde resin.

(a) In accordance with the co-pending application of Harry Borden Marshall and Mary Krizsan, S. N. 299,278, now Patent 2,772,140, a wide range of phenolic derivatives of waste sulphite liquor may be prepared, and any of these may be treated with a reactive aldehyde to form a watersoluble thermosetting binder. However, we prefer, for economic reasons, to use as a starting material the derivative of waste sulphite liquor and phenol (hydroxy benzene) or waste by-product phenols, for example the crude phenolic mixture recovered from the caustic scrubbers of a petroleum refinery.

We have found that the product prepared from a derivative of waste sulphite liquor containing less than 5 parts of combined phenol per parts of sulphite liquor solids lacks water resistance, but may be used in applications where water resistance is not required. Phenol derivatives of waste sulphite liquor containing more than 45 parts of phenol per 100 parts of sulphite liquor solids contain excessive amounts of water-insoluble condensation products. This heterogeneous mixture may be treated with a reactive aldehyde to form a thermosetting binding material which is only partially water-soluble. Alternatively, the insoluble material may be separated and dissolved in a suitable solvent such as alcohol, or it may be rendered water-soluble by sulphonation, and then treated with a reactive aldehyde to form a soluble thermosetting binding material. Such procedures are within the scope of this invention. However, we prefer to treat a phenol derivative of Waste sulphite liquor containing between 5 and 45 parts or" combined phenol per 100 parts of sulphite liquor solids with a reactive aldehyde to form a watersoluble product which may be condensed by the action of heat to an insoluble, water-resistant binding material.

In the co-pending application of Harry Borden Marshall and Mary Krizsan, Serial No. 299,278, now Patent 2,772,140, it was shown that the reaction of waste sulphite liquor with phenol does not go to completion, and that conclude therefore that this process results in the formation of a true eopolymer of the phenol and the phenol Patented June 4,1951

3. derivative of sulphite liquor with the reactive aldehyde, and'this process is included'in our invention.

(b) Any aldehyde which. may be condensed readily with phenol may be. used in. our. process,..but for economicreasons. we p'ltefer to, useformaldehyde'or furfural; The.

optimum quantity. of aldehyde, is.dependent on the type and amount of phenol. used. in the. preparation. oi the prior to application to the waste wood materiall During this. time partial reaction of the aldehyde with the phenol derivative. of waste sulphiteliquor occurs-, with the. result that. less aldehyde is lost. by evaporation during subsequent handling, and less time is required. to. complete the. reaction in the press. While; this: period of heating is. not essential to-the successful application. of our invention,v we prefer to heat the mixture of. reactantsat 100C. for 1 hour after the addition of the aldehyde and-prior to its application to the waste-woodmaterial.

For the application of our inventioninthe manufactureof dry process synthetic boards, theliquidbinder, may be applied. to. the wastewood. material by. any suitablemixing technique in. amounts, of 220% of the wood fibre, on a dry solids basis. The strength ofthe pressed board is dependent to a considerable extent on. the, moisture. contentot the mixture of binder and waste wood fibres prior to pressing.

character of the wood waste. It must bedetermined by experiment; for each formulation but. in general lies between and 30%.

The mixture. of binder andwood waste is-formedinto. a mat and is then pressed between heated-plattens until the binder has been converted to the insoluble state. The optimum temperature varies between l00.and,14.0f CL,

' depending upon theformulation used, and. must.also.be-

established by experiment. The timerequiredtoinsolubilize the binder varies with the thickncssof theboard, 10 minutes beingrequired for aboard 0.2 inch. thick and: 30 minutes being required for a board. 0.5 inch thick. Pressure is. without important effect onthe cure ofthe binder and may. bevaried. according to the: density and. strength requiredin the resulting board.v

The following description. of experiments which have been performed by us will serve to illustratethe. application of our invention. It is to be understood. that our invention is not limited to thematerials. andconditions described in these experiments which are to be considered as examples only.

Example 1.-Illustrating thepreparation Ufa-them") setting binding material from formaldehyde and a phenol derivative of waste sulphite liquor- 100 millilitres of an aqueous solution: of a, phenol derivative ofwaste sulphite liquor; (containing 24;8 grams.

The optimum. moisture content is. dependent. both-on the type of binder. used and. onthe for Testing Materials specification No. D-1037, and was found to have a tensile strength of 1,2'55p. s. i.

Example 2.-Illustrating the preparation of a thermosetting binding material from furfural and a phenol derivative of waste sulphite liquor A mixtureof 28.5 grams of furfural. and millilitres: of an aqueous solution of a phenol derivative of waste sulphite liquor (containing 24.8 grams of dry solids of which 9.3 grams was combined phenol) was heatedat 100 C. for one hour. 26 grams, of, this solution was thoroughly mixed with 100 grams ofiwood' shavings. The mixture was adjusted to a moisture content of 10%. and pressed at 500 p. s. i. pressure for; 10. minutes between 8 inch square plattens at C The product had a thickness of 0.132 inchandv a tensile strength of 1,890

Example 3.'-Illi1strating the preparationof'a'thermosettihgbinding material'from fbrmaldeliyde and a creso derivative ofwaste' sulphite liquor The mixedcresols. used-.in this. experiment were. re.- covered. from. the alkaline. scrubbers of. a. petroleum. re,-,

finery. l00millilitres;ofia.solution of this cresol. derivative 0t waste sulphite. liquor (containing. 25.0 grams of dry. solidsof which 7.0. grams was. combined cresols) was:

heated at.1003 C. for one hour with 5.8 grams. of: 36% formaldehyde. solution. 39 grams: of this. solution; was.

mixed" with. 100. grams of 6. to. 10. mesh shredded wood; shavings... the moisture contentxwas; adjusted to 15%,.and

the-mixture was pressed; at15.00..p.. s. i; for lflirm'nutesbetween 8- inchsquare-plattens at C. The resulting:

product had a thickness of' 0.138 inch and a. tensile strength-of: 1,582p. s. i.

Example 4.--Illizstrating,the preparation of a thermostatting binding material from fizrfural anda cresol derivative of 'waste sulphite liquor,

8 inch' square plattens. The. resulting product had a. thickness-of 0;1'33' inch anda. tensile strength of 2,260

p. s. i.

Example 5.Illi4strating the preparation ofa thermosefl tingbin'di'r'zg material from formaldehyde andja phenol. derivative of 'waste sulphite liquor containingfree plienol 100.- millilitres. of an aqueous solution a of aphenol derivative-ofiwaste sulphite, liquor: (Containing-.3 1.0 grams of. dry solidsiof. which 8.5Tgrams was combined" phenol and 8.5 grams: was: free phenol)v was, heated at 100 C. for: 10 minutes with-.68. grams of 36% formaldehyde solu-- tion. 30 gramsnf this solution was applied to 100 gran1s of 6. to. 10. meshshredded, wood shavings, and pressed 8t'1T1QTC;.fQI' 10 minutes between 8injch square plattens. product had'a thicknessef 0.142 inch and; a tensile strength of 1,5'60p. s. i.

Example 6.-Illustrating the preparation of a thermostat tingj binding material fromjformaldehyde "and a phenol derivative of waste -sulphite liquor of low phenol content 100: millilitres :ofa solutionof a" phenol, derivative or waste .snlphiteliquor (containing 26.1 grams of dry-solids of which;- only, 1.9 grams was. combinedphenoll was heated. at 100.? C. for one hourwith-7.8 grams of; 36% formaldehyde'solution. 3.8 grams ofthis. solution was mixed with IOOgrams of 6" to 10 mesh shredded wood shavings and pressed at 120 C. for minutes. The product had a tensile strength of 1,120 p. s. i. and a thickness of 0.142 inch.

Example 7.-Illustrating the efiect of cresol content on the strength of binders prepared from formaldehyde and cresol derivatives of waste sulphite liquor A series of cresol derivatives of waste sulphite liquor were prepared with varying contents of combined cresol, as shown in Table I. Each cresol derivative was then converted to a thermosetting binder by heating 19 grams of an aqueous solution containing 7 grams dry solids with 7 grams of 36% formaldehyde solution for 1 hour at 100 C. Synthetic boards were then made from each of the resulting solutions by applying 3.7 grams of the solution to 10.0 grams of shredded wood shavings and pressing the mixture for 10 minutes at 130 C. Six specimens of each board were prepared, three of which were immersed in water for 1 hour after pressing. All samples were conditioned at 50% relative humidity and 70 F. prior to determination of flexural strength. The results of flexural tests shown in Table I, are given in arbitrary units and are only suitable for comparative purposes. They indicate that the binders have high water resistance and that strength increases slightly with increasing cresol content.

Example 8.-Illustrating the efiect of formaldehyde content on the strength of binders prepared from formaldehyde and phenol derivatives of waste sulphite liquor A series of binders was prepared from a phenol derivative of waste sulphite liquor containing 37.4% combined phenol. 100 ml. portions of a 24.8% solution of this material were heated with various amounts of 36% formaldehyde solution, as shown in Table II, for 1 hour at 100 C. Synthetic boards were then made from each of the resulting solutions by applying 4.0 grams of the solution to 10 grams of shredded wood shavings and pressing the mixture at 100 C. for 10 minutes. Two speci mens of each board were prepared, one of which was immersed in water for 1 hour after passing. All samples were conditioned at 50% relative humidity and 70 F. prior to determination of flexural strength. The results, given in arbitrary units in Table II, show TABLE II Strength (lbs.) Formaldehyde Content (grams 36% formaldehyde solution/100 ml. solution) Dry After Immersion What We claim as our invention is:

l. A process for the preparation of a thermosetting binder from waste sulphite liquor which comprises reacting a Waste sulphite liquor phenol reaction product having a phenol content of between 5 percent and 45 percent by weight, such waste sulphite liquor phenol reaction product being obtained by the condensation of a phenol with decationized waste sulphite liquor, said phenol being selected from the group consisting of monohydric, dihydric and trihydric phenols and combinations thereof, with an aldehyde containing fewer than 6 carbon atoms, said aldehyde being present in the ratio of from A2 mole to 5 moles per mole of phenol.

2. The process of claim 1 wherein said aldehyde is formaldehyde.

3. The process of claim 1 wherein said aldehyde is furfural.

4. The process of claim 1 wherein said aldehyde is acetaldehyde.

5. A process for the preparation of a thermosetting binder from waste sulphite liquor which comprises reacting a. waste sulphite liquor phenol reaction product having a phenol content of between 5 percent and 45 percent by weight, such waste sulphite liquor phenol reaction product being obtained by the condensation of a phenol with decationized waste sulphite liquor, said phenol being selected from the group consisting of monohydric, dihydric and trihydric phenols and combinations thereof and containing excess unreacted phenol, with an aldehyde :ont-aining fewer than 6 carbon atoms, said aldehyde being present in the ratio of from As-mole to 5 moles per mole of phenol.

References Cited in the file of this patent UNITED STATES PATENTS 2,045,049 Noerr et a1 June 23, 1936 2,099,717 Alles Nov. 23, 1937 2,221,778 Collings et al. Nov. 19, 1940 FOREIGN PATENTS 519,848 Great Britain Apr. 8, 1940 

1. A PROCESS FOR THE PREPARATION OF A THERMOSETTING BINDER FROM WASTE SULPHITE LIQUOR WHICH COMPRISES REACTING A WASTE SULPHITE LIQUOR PHENOL REACTION PRODUCT HAVING A PHENOL CONTENT OF BETWEEN 5 PERCENT AND 45 PERCENT BY WEIGHT, SUCH WASTE SULPHITE LIQUOR PHENOL REACTION PRODUCT BEING OBTAINED BY THE CONDENSATION OF A PHENOL WITH DECATIONIZED WASTE SULPHITE LIQUOR, SAID PHENOL BEING SELECTED FROM THE GROUP CONSISTINGOF MONOHYDRIC, DIHYDRIC AND TRIHYDRIC PHENOLS AND COMBINAITONS THEREOF, WITH AN ALDEHYDE CONTAINING FEWER THN 6 CARBON ATOMS, SAID ALDEHYDE BEING PRESENT IN THE RATIO OF FROM 1/8 MOLE TO 5 MOLES PER MOLE OF PHENOL. 